W1 Haematopoietic System and Component Parts Part 2 Flashcards
(33 cards)
what are the primary lymphoid organs?
thymus and bone marrow (bursa of fabricus in birds) and maturation of T and B lymphocytes
what are the secondary lymphoid organs?
spleen, lymph nodes, MALT/GALT, tonsils and adenoids - initiation of immune response
what are the tertiary lymphoid organs?
ectopic lymphoid tissues that develop at sites of chronic inflammation in non-lymphoid organs
what is the thymus?
an organ that provides environment for T cell development, it has lobes divided into lobules by trabeculae
what parts do each lobe of the thymus have?
outer cortex and inner medulla
what happens to thymocytes that are not selected?
they undergo apoptosis and are phagocytosed by macrophages
what is a thymocyte?
an immune cell present in the thymus that undergoes transformation into a T Cell
what is the major role of the spleen?
to survey the presence of foreign antigens in blood
what is the spleen?
a secondary lymphoid organ that consists of a capsule with fibrous partitions (red and white fibrous pulp)
what does the red pulp of the spleen do?
filters and removes damaged or aged red blood cells via phagocytosis by macrophages
what is the role of white pulp in the spleen?
to bring lymphocytes together to mount immune responses against foreign antigens (B and T cells circulate in the pulp entering via terminal arterioles and leaving via blood vessels in the red pulp)
where do T cells localise within (they interact with dendritic cells here)?
periarteriolar sheath (PALS)
where do B cells localise (where they interact with specialised dendritic cells)?
in follicles
what do B cells responding to antigens form? what happens here?
form germinal centres where they mature and differentiate
blood components from capillaries enter tissues forming extracellular fluid that provides nutrients and gas exchange, what does this fluid drain into?
vessels called lymphatics
what are lymph nodes?
small and bean shaped tissue aggregates at junctions of major lymph vessels, they are located within the lymphatic system to allow the surveillance of antigens and initiate the adaptive immune response
what size are lymph nodes?
1-25mm, larger during infection
what are the three parts of a lymph node?
cortex, paracortex and medulla (surrounded by a capsule)
lymph carrying antigens and dendritic cells enter via what?
afferent lymphatics
what do lymphocytes from the blood enter via?
high endothelial venules (HEV)
do T cells migrate and localise in the paracortex or cortex?
paracortex (B cells in the cortex)
lymphocytes migrate through the medulla and exit the node via what?
efferent lymphatics
name three lymph nodes:
any three of:
submandibular
cervical
axillary
popliteal
inguinal
what is MALT?
mucosal associated lymphoid tissue - diffusely distributed lymphoid tissues in lining of gastro. , resp. and urogenital tracts
